Turbocharger bearing fluid film surface and method

ABSTRACT

A bearing system and method may include a bearing element that may have a first surface. A mating element may have a second surface that may face the first surface. A fluid film interface may be defined between the first and the second surfaces. The mating element may rotate about an axis and relative to the bearing element. An axial direction may be defined parallel to the axis. A radial direction may be defined perpendicular to the axis. The first surface may have a profile that may vary in the axial direction and that may varies in the radial direction. The profile may direct a fluid present in the fluid film interface in a direction or directions having circumferential and/or axial components.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/084,685 filed Mar. 30, 2016.

TECHNICAL FIELD

The field to which the disclosure generally relates includes bearingsystems for rotating elements and in particular, includes bearingsystems in turbochargers.

BACKGROUND

Bearings typically support rotating elements in a low friction manner,and may be employed in a variety of environments. For example, aturbocharger, such as that used to charge the intake air of an internalcombustion engine, may include a compressor driven by a turbine. Theturbine may be connected to the compressor by a common shaft that may besupported for rotation by bearings. The shaft and its connected turbineand compressor wheels may rotate at speeds that approach hundreds ofthousands of revolutions per minute. In addition, the turbocharger mayoperate in a high temperature exhaust gas environment.

SUMMARY OF ILLUSTRATIVE VARIATIONS

A number of variations may involve a bearing system that may include abearing element that may have a first surface. A mating element may havea second surface that may face the first surface. A fluid film interfacemay be defined between the first and the second surfaces. The matingelement may rotate about an axis and relative to the bearing element. Anaxial direction may be defined parallel to the axis. A radial directionmay be defined perpendicular to the axis. The first surface may have aprofile that may vary in the axial direction and that may varies in theradial direction. The profile may direct a fluid present in the fluidfilm interface in both the axial and circumferential directions.

A number of additional variations may involve a method and may includeproviding a machine with a rotor. Magnetic levitation of the rotor maybe provided. The rotor may be provided with a cutting tip. The rotor maybe directed through a radial, or may be combined with axial, trajectoryusing the magnetic levitation. The profile of the bearing element on theinner circumferential surface may be cut with the cutting tip.

Other illustrative variations within the scope of the invention will beapparent from the detailed description provided herein. It should beunderstood that the detailed description and specific examples, whiledisclosing variations within the scope of the invention, are intendedfor purposes of illustration only and are not intended to limit thescope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Select examples of variations within the scope of the invention willbecome more fully understood from the detailed description and theaccompanying drawings, wherein:

FIG. 1 is a schematic illustration of a rotating system according to anumber of variations.

FIG. 2 is a schematic illustration of a rotating system according to anumber of variations.

FIG. 3 is a schematic illustration of part of a bearing system for usewith a product according to a number of variations.

FIG. 4 is a schematic cross sectional illustration of part of a bearingsystem for use with a product according to a number of variations, takenalong the line 4-4 indicated in FIG. 3.

FIG. 5 a schematic illustration of part of a bearing system for use witha product according to a number of variations.

FIG. 6 is a schematic cross sectional illustration of part of a bearingsystem for use with a product according to a number of variations, takenalong the line 6-6 indicated in FIG. 5.

FIG. 7 is a schematic sectioned perspective illustration of part of abearing system for use with a product according to a number ofvariations.

FIG. 8 is a schematic sectioned perspective illustration of part of abearing system for use with a product according to a number ofvariations.

FIG. 9 is a schematic sectioned perspective illustration of part of abearing system for use with a product according to a number ofvariations.

FIG. 10 is a schematic sectioned perspective illustration of part of abearing system for use with a product according to a number ofvariations.

FIG. 11 is a schematic sectioned perspective illustration of part of abearing system for use with a product according to a number ofvariations.

FIG. 12 is a two dimensional diagram of a bearing inner profileaccording to a number of variations with location angles on thehorizontal axis versus axial location ratio on the vertical axis.

FIG. 13 is a schematic diagram of a method of making a product accordingto a number of variations.

FIG. 14 is a schematic illustration of a cutting tip according to anumber of variations.

FIG. 15 is a schematic illustration of a step in a method of making aproduct according to a number of variations.

FIG. 16 is a schematic illustration of a step in a method of making aproduct according to a number of variations.

FIG. 17 is a schematic illustration of a step in a method of making aproduct according to a number of variations.

FIG. 18 is a schematic illustration of a step in a method of making aproduct according to a number of variations.

DETAILED DESCRIPTION OF ILLUSTRATIVE VARIATIONS

The following description of the variations is merely illustrative innature and is in no way intended to limit the scope of the invention,its application, or uses.

In a number of variations as illustrated in FIG. 1, a product 10 may beused with a rotating system, which for purposes of illustration may be aturbocharger system 12 for use with an engine. The turbocharger system12 may include a turbine wheel 14 that may exist in a continuous highvelocity jet of exhaust gases when the engine is running. Theturbocharger system 12 may include a compressor wheel 16 that may beconnected to the turbine wheel 14 by a shaft 18 so that the turbinewheel 14 and the compressor wheel 16 rotate together at a variablerotational speed. The shaft 18 may extend through a housing 20. Abearing system 22 may be contained in the housing 20, and the shaft 18may extend through the bearing system 22. The shaft 18 may be supportedby the bearing system 22 to rotate with low friction resistance. Theshaft 18 may generally rotate about an axis and the reference lineindicates the axial direction 11. The reference line 11 may beintersected by a reference line that may indicate the radial direction15, which extends ninety degrees relative to the axis and may bedirected away from the axis in any of 360 angular degrees around theaxis.

In a number of variations a bearing system such as the bearing system 22may provide efficient, low friction operation with an ability to manageencountered forces in a challenging environment. The bearing system 22may be a hydrodynamic bearing system supplied with a lubricant through agallery system 23 to inhibit contact, provide damping, and/or to controlmotion. The bearing system 22 may use fully floating journal typebearings 24 and 26 and the shaft 18 may be a mating element relative tothe bearings 24 and 26. The bearings 24 and 26 may be contained in abore 28 of the housing 20 and may be provided with a retention mechanismto maintain their axial position, such as clip rings (not shown), orother devices known in the art. The bearing 24 and 26 may encircle theshaft 18 and may freely float within their retention system, which mayinclude rotation with the shaft 18 and within the housing 20. Thebearing 24 and 26 may generally rotate at a slower speed than the shaft18 so that relative rotation occurs at their mating interfaces. As aresult, with the bearings 24 and 26 there may be two hydrodynamic oilfilm interfaces, which may include an outer film interface 30 betweenthe housing 20 and the bearings 24, 26, and an inner film interface 32between the bearings 24, 26 and the shaft 18.

In a number of other variations a product 40 as shown in FIG. 2, mayinclude the turbine wheel 14 and the compressor wheel 16 connected bythe shaft 18. The shaft 18 may be supported in the housing 20 by abearing system 42. The bearing system 42 may be a semi-floating bearingsystem. A pin 44, or other anti-rotation devices as known in the art,may engage the housing 20 and the bearing system 42. The bearing system42 may float between the shaft 18 and the housing 20 but may berestrained from rotating relative to the housing 20 by the pin 44. Theshaft 18 may rotate relative to the bearing system 42 and the housing20. The semi-floating bearing system 42, in this case, may be an exampleof a single, integral or assembled unit comprising two separatesemi-floating bearing ends, adjoined by a center connecting section 41.One semi-floating end is made up of inner film interface 49 and outerfilm interface 47, and the other semi-floating end made up of an innerfilm interface 48 and an outer film interface 46. In other variationseach semi-floating bearing end floats separately without adjoiningcenter section 41, with each having a separate anti-rotation device. Thebearing system 42 may have four or more oil film interfaces, which mayinclude two or more outer film interfaces 46, 47 between the housing 20and the bearing system 42, and two or more inner film interfaces 48, 49between the bearing system 42 and the shaft 18. The inner filminterfaces 48, 49 may be a hydrodynamic oil film interface. The outerfilm interfaces 46, 47 may operate as a squeeze film interface fordamping between the bearing system 42 and the housing 20. In a number ofvariations the products 10, 40 may include a thrust bearing system (notshown), as known in the art, which may, or may not, be integral to theradial bearing systems.

With reference to FIGS. 3 and 4, in a number of variations a bearing 50is illustrated, which may be used in the bearing system 22 or thebearing system 42 for the inner film interfaces 48, 49. The bearing 50may be of a generally hollow cylindrical shape. The bearing 50 may havean axially extending opening 52 that may define an inner circumferentialsurface 54 of each film interface 48, 49, and each may be a variation ofthe other. The inner circumferential surface 54 may extend around the360 degree circumference of the opening 52 from a first end 56 to asecond end 58 of the bearing 50. The bearing 50 may have an outermostperimeter 60 that extends around the bearing 50 and that defines anouter circumferential surface 62. The outer circumferential surface 62may extend from the end 56 to the end 58 and may have circumferentialoil grooves (shown in FIG. 2). The bearing 50 may have a wall 64 thatmay exist between the inner circumferential surface 54 and the outercircumferential surface 62. A number of openings 68, 69 may extend inthe radial direction 15 through the wall 64 from the outercircumferential surface 62 to the inner circumferential surface 54. Theopenings 68, 69 may cooperate with the gallery system 23 to supplylubricant to the inner circumferential surface 54 and the interfacingshaft 18.

With reference to FIGS. 5 and 6, in a number of variations a bearing 70is illustrated, which may be used in the bearing system 22 or thebearing system 42. The bearing 70 may be of a generally hollowcylindrical shape. The bearing 70 may have an axially extending opening72 that may define an inner circumferential surface 74. A first dam 76may be formed at an end 77 of the bearing 70. A second dam 78 may beformed at an opposite end 79 of the bearing 70 from the end 77. The dams76 and 78 may have axial openings 80 and 81 respectively, that may becircular in shape and that may have an open diameter that is smallerthan the open diameter of the opening 72, and the difference may beexaggerated in FIG. 6 for visible clarity. The inner circumferentialsurface 74 may extend around the 360 degree circumference of the opening72 and may extend axially from the first dam 76 to the second dam 78.Each dam 76, 78 may have surface variations to each other, and may alsohave profiled surfaces. As a result, the axial extending opening 72 maynot extend all the way to the ends 77, 79 of the bearing 70. The bearing70 may have an outermost perimeter 82 that extends around the bearing 70and that defines an outer circumferential surface 84. The outercircumferential surface 84 may extend from the end 77 to the end 79 andmay have circumferential oil grooves (shown in FIG. 2). The bearing 50may have a wall 86 that may exist between the inner circumferentialsurface 74 and the outer circumferential surface 84. A number ofopenings 88 may extend in the radial direction 15 through the wall 86from the outer circumferential surface 84 to the inner circumferentialsurface 74. The opening or openings 88 may cooperate with the gallerysystem 23 to supply lubricant to the inner circumferential surface 74and the interfacing shaft 18. The dams 76, 78 may assist in maintainingthe lubricant at the oil film interface at the inner circumferentialsurface 74, and regulating oil flow out the ends 77, 79.

With reference to FIG. 7, a fragmented half of a bearing 90 is shown forvisibility of the inner circumferential surface 92. The bearing 90 mayrepresent the bearing 50 and/or the bearing 70. The bearing 90 may be afully floating bearing or a semi-floating bearing or another type withan inner hydrodynamic oil film interface at the inner circumferentialsurface 92. The inner circumferential surface 92 of the wall 93 may havea profile 94 shaped to provide directed convergence 95 of the lubricantat the interface between the bearing 90 and the shaft 18, and may beformed without steps that may have distinct edges. Convergence mayindicate a movement and accumulation of the lubricant from one or moreareas of the inner circumferential surface 92 to one or more other areasof the inner circumferential surface 92 at the interface with the shaft18. Directed convergence may include convergence with flow components inone or more directions which may include the axial direction 11 and acircumferential direction 96. The circumferential direction 96 may be adirection following the circumference of the inner circumferentialsurface 92 around the axis of the bearing 90 and the shaft 18. In thepresent example, the directed convergence may have components in thecircumferential direction 96 and in the axial direction 11 toward amidpoint 98 along the axial length of the bearing 90 and away from eachof the ends 97, 99 of the bearing 90. The profile 94 of the innercircumferential surface 92 may be shaped to effect the directedconvergence.

With reference to FIG. 8, in a number of variations the profile 94 ofthe of the inner circumferential surface 92 may be demonstrated by anumber of discrete reference lines 101, 102, 103, 104 and 105 selectedalong the axial length of the bearing 90. The reference lines 101-105are shown extending along 180 degrees of the inner circumferentialsurface from zero degrees at the section edge 106 to 180 degrees at thesection edge 108. It should be understood that the inner circumferentialsurface extends 360 degrees around the axis for a complete non-sectionedbearing 90. The profile 94 at each of the reference lines 101-105 mayhave a varying height created by a varying thickness of the wall 93. Theprofile 94 may have a peak 109 running in a ridge through points 110,111, 112, 113 and 114 and alternating valleys, one running throughpoints 115, 116, 117, 118, 119 and another running through points 120,121, 122, 123, 124. For example, the reference line 101 may follow theprofile 94 through a valley which may be the lowest at point 120, overthe peak 108 at point 110 and through another valley at point 115. Thepeak points 110-114 and valley points 115-119 and 120-124, may be shownexaggerated for visual clarity of their difference in height. In anumber of variations the difference in heights between the peak points110-114 and the valley points 115-119 may be in the normal range of 4-30microns. The alternating peaks and valleys around the circumference ofthe inside of the bearing 90 may affect the circumferential convergenceof the oil film in the interface between the bearing 90 and the shaft18. The lubricant may be directed in an up-hill fashion, for examplefrom the valley 120 up toward the peak 110 for convergence at therelatively high locations forming a number of wedges of lubricationaround the perimeter to the shaft 18 which may reduce vibration, noise,may increase stability and enable higher rotational speeds. In addition,the peak points 110-114 along the length of the bearing 90 may belocated at varying angular distances from the edge 106. For example, thepoint 110 may be located a distance of ninety degrees from the edge 106.The point 111 may be located at a distance of seventy-eight degrees fromthe edge, and the point 112 may located at a distance of sixty-sixdegrees from the edge 106 and may be at the midpoint 98 along the axiallength of the bearing 90. The peak may transition back to seventy-eightdegrees at the point 113 and to ninety degrees at the point 114. As aresult, the ridge defined by the peak 108 may shift forward in rotationof the shaft 18 moving from the ends 97 and 99 toward the midpoint 98.As a result, the lubricant may be directed in an inward direction awayfrom the ends 97 and 99 fashion, having a convergence component in anaxial direction toward the midpoint 98. This may assist in maintainingthe lubricant from leaking out the ends 97, 99 and in the interfacebetween the bearing 90 and the shaft 18. As a result the bearing 90 mayprovide directed convergence in both the circumferential direction andthe axial direction.

In a number of variations as illustrated in FIG. 9, a bearing set 130 isshown as a fragmented half section for visibility of the innercircumferential surfaces 132 and 134 of the bearings 136 and 138. Thebearings 136 and 138 may be disposed in spaced apart locations on theshaft 18 and in the housing 20. The bearings 136 and/or 138 mayrepresent the bearing 50 and/or the bearing 70. The bearings 136, 138may be fully floating bearings or a semi-floating bearings or anothertype with an inner hydrodynamic oil film interface at the innercircumferential surfaces 132, 134. The inner circumferential surface 132of the bearing 136 may have a profile 133 shaped to provide directedconvergence 135 of the lubricant at the interface between the bearing136 and the shaft 18. The directed convergence 135 may includeconvergence components in multiple directions which may include theaxial direction 11 and a circumferential direction 137. In the presentexample, the directed convergence may have a component in thecircumferential direction 137 from the edge 139 to the edge 131. Thedirected convergence may also have a component in the axial direction 11along the axial length of the bearing 136 away from the end 140 andtoward the end 142. The profile 133 of the inner circumferential surface132 may be shaped to effect the directed convergence. The innercircumferential surface 134 of the bearing 138 may have a profile 144shaped to provide directed convergence 145 of the lubricant at theinterface between the bearing 138 and the shaft 18. The directedconvergence 145 may include convergence components in two directionswhich may include the axial direction 11 and a circumferential direction137. In the present example, the directed convergence may be directed inthe circumferential direction 137 from the edge 148 toward the edge 146.The directed convergence may be directed in the axial direction 11 alongthe axial length of the bearing 138 away from the end 150 and toward theend 152. The profile 151 of the inner circumferential surface 134 may beshaped to effect the directed convergence.

With reference to FIG. 10, in a number of variations the profile 133 ofthe of the inner circumferential surface 132 may be demonstrated by anumber of discrete reference lines 161, 162 and 163 selected along theaxial length of the bearing 136. The reference lines 161-163 are shownextending along 180 degrees of the inner circumferential surface 132from zero degrees at the section edge 165 to 180 degrees at the sectionedge 167. It should be understood that the inner circumferential surfaceextends 360 degrees around the axis for a complete non-sectioned bearing130. The profile 133 at each of the reference lines 161-163 may have avarying height created by a varying thickness of the wall 139. Theprofile 133 may have a peak 168 running in a ridge through points 161,162 and 163 and alternating valleys, one valley running through points170, 171, 172 and another valley running through points 173, 174 and175. For example, the reference line 161 may follow the profile 133through a valley which may be the lowest at point 173, over the peak 168at point 161 and through another valley at point 170. The peak points161-163 and valley points 170-172 and 173-175, may be shown exaggeratedfor visual clarity of their difference in height. The alternating peaksand valleys around the circumference of the inside of the bearing 130may affect the circumferential convergence of the oil film in theinterface between the bearing 130 and the shaft 18. The lubricant may bedirected in an up-hill fashion, for example from the valley 173 uptoward the peak 161 for convergence at the relatively high locations. Inaddition, the peak points 161-163 along the length of the bearing 130may be located at varying angular distances from the edge 165. Forexample, the point 161 may be located a distance of eighty degrees fromthe edge 165. The point 162 may be located at a distance ofseventy-eight degrees from the edge, and the point 163 may be located ata distance of sixty-six degrees from the edge 165. The peak ridge may betransition closer to the edge 165 moving from the end 176 to the end177. As a result, the ridge defined by the peak 168 may shift forward inrotation of the shaft 18 moving from the ends 176 to end 177. As aresult, the lubricant may be directed in an inward direction away fromthe end 176, for convergence with an axial component in the directiontoward the end 177 which may be disposed to lead to an area 179 betweenthe bearings 136 and 138. This may assist in maintaining the lubricantfrom leaking out the outboard end 176 relative to the housing 20 whichmay be toward the turbine wheel 14. As a result the bearing 130 mayprovide directed convergence with components in both the circumferentialdirection and the axial direction.

In a number of variations in the bearing 138, the profile 151 of the ofthe inner circumferential surface 133 may be demonstrated by a number ofdiscrete reference lines 181, 182 and 183 selected along the axiallength of the bearing 138. The reference lines 181-183 are shownextending along 180 degrees of the inner circumferential surface 134from zero degrees at the section edge 185 to 180 degrees at the sectionedge 187. It should be understood that the inner circumferential surface134 extends 360 degrees around the axis for a complete non-sectionedbearing 138. The profile 151 at each of the reference lines 181-183 mayhave a varying height created by a varying thickness of the wall 189.The profile 151 may have a peak 190 running in a ridge through points184, 186 and 188 and alternating valleys, one valley running throughpoints 191, 192, 193 and another valley running through points 194, 195,196. For example, the reference line 183 may follow the profile 151through a valley which may be the lowest at point 199, over the peak 190at point 184 and through another valley at point 191. The peak points184, 186, 188 and valley points 191-193 and 194-196, may be shownexaggerated for visual clarity of their difference in height. Thealternating peaks and valleys around the circumference of the inside ofthe bearing 138 may affect the circumferential convergence of the oilfilm in the interface between the bearing 138 and the shaft 18. Thelubricant may be directed in an up-hill fashion, for example from thevalley 194-196 up toward the peak 190 for convergence at the relativelyhigh locations. In addition, the peak points 184, 186, 188 along thelength of the bearing 138 may be located at varying angular distancesfrom the edge 185. For example, the point 188 may be located a distanceof eighty degrees from the edge 185. The point 186 may be located at adistance of seventy-eight degrees from the edge 185, and the point 184may be located at a distance of sixty-six degrees from the edge 185. Thepeak ridge may transition closer to the edge 185 moving from the end 198to the end 199. As a result, the ridge defined by the peak 190 may shiftforward in rotation of the shaft 18 moving from the end 198 to end 199.As a result, the lubricant may be directed in an inward direction awayfrom the end 198, for convergence in an axial direction toward the end199 which may be disposed to lead to an area 179 between the bearings136 and 138. This may assist in maintaining the lubricant from leakingout the outboard end 198 relative to the housing 20 which may be towardthe compressor wheel 16. As a result the bearing 138 may providedirected convergence with components in both the circumferentialdirection and the axial direction. The bearings 136 and 138 may be usedin a pair with the axial convergence component directed to an area 179inside the housing 20.

In a number of variations as illustrated in FIG. 11 a bearing 200 isshown sectioned with part of its length removed. The bearing 200 may beused in the bearing assembly 22 or 42. The bearing 200 may have an outercircumferential surface 202 which may face the housing 20 in the bore28. The bearing 200 may have an inner circumferential surface 204, whichmay face the shaft 18. A hydrodynamic oil film interface may be definedbetween the inner circumferential surface 204 and the shaft 18. Theinner circumferential surface may extend in the axial direction 11 froma dam 208 at the end 210 to another dam at the sectioned away other endof the bearing 200. The profile 212 of the inner circumferential surface204 visible at the junction 214 with the dam 208, may be a smoothtransition rather than a discernable edge. The profile 212 may bedefined by a varying thickness of the wall 216 of the bearing 200. Thedam 208 may define an opening 218 inside a circular wall edge 220 thatmay face inward toward the axis 11. The edge 220 may be a minimumdistance 206 away from the profile 212 to inhibit oil movement outwardpast the dam 208. The opening 218 may have a circular profile around itscircumference. Weep holes and axial oil feed/drain grooves, which areomitted in the illustrations, may be included. The profile 212 mayundulate around the circumference of the inner circumferential surface204 between alternating peaks 221, 222 and 223, and valleys 224, 225 and226. The number of peaks and valleys may vary depending on therotational speed of the application and the size of the bearing. Thevariation of the thickness of the wall 216 is exaggerated for thepurposes of providing visual clarity. The wall thickness 230 at thelowest point of the valley 225 may be in the normal range of 4-30microns less than the wall thickness 232 at the highest point of thepeak 223. The profile 212 may include smooth ramp like structures fromthe valleys to the peaks, such as from valley 226 to peak 221.

In a number of variations the profile 212 of the ridges created by thepeaks, such as peak 221 moves clockwise (as viewed in FIG. 11), movinginward from the end 210. More specifically, the shaft 18 may rotate inthe rotation direction 236. The top of the ridge defined by the peak 221may be represented by the curve 238. Moving inward from the dam 208, thecurve 238 moves clockwise away from the axial direction 11, and at anacute angle 240 relative to the axial direction 11. As a result, thepoint 242 will reach an axially directed line along the outer diameterof the shaft 18 prior to the point 244. As a result, oil film may have acircumferential component for convergence uphill, such as from thevalley 224 toward the peak 238 in the circumferential direction 246, andoil film may also have an axial component for convergence in an axiallyinward direction from the dam 208 toward the section's broken edge 248,providing directed convergence.

In a number of variations as illustrated in FIG. 12, the profile 212 ofthe bearing 200 may be illustrated in the form of a chart 249, with theunderstanding that the complete bearing is represented include the partremoved from the sectioned view of FIG. 11. The inner circumferentialsurface 204 is shown in two-dimensional form in the flat chart 249. Thechart may be described as a map of the inner circumferential surface204. The vertical axis 250 represents a non-dimensionalized ratio of theaxial location along the inner circumferential surface 204 in the axialdirection 11 from one of its ends to another, with zero being at one endand 1.0 being at the other end. So, the axial ratio represents thedistance along the length of the bearing in the axial direction as aratio to the total length of the bearing. The actual bearing length, ordistance from ratio zero to ratio 1.0 may be in the neighborhood of abearing length of L in the current variation. The bearing length L maybe determined using the L/D ratio, where L is bearing length and D isbearing inner diameter, and the ratio L/D=0.2 to 1.5. However, thelength may vary depending on the application. The horizontal axis 252represents location around the circumference of the innercircumferential surface 204 from zero to three hundred and sixtydegrees. For example, the chart 249 illustrates the C-shaped arc-likeridge and trough character of the peaks 221-223, and the valleys224-226, respectively. The chart 249 shows zero/three hundred and sixtyat the top of the peak 221 at the midpoint line 251 of the bearing 200at ratio 0.5 on the axis 250 and angle zero/three hundred and sixty onthe axis 252, designated by reference number 253. As demonstrated, whenmoving away from the midpoint line 251, the peak 221 moves to the rightin the chart 249 to approximately twenty-four degrees around the innercircumferential surface 204 at points 254 and 256, at zero and 1.0location ratio respectively, on the bearing 200. Similarly, the chart249 shows the valley 224, wherein along the midpoint line 251, thelowest point 258 of the valley 224 may be located at approximately sixtydegrees along the inner circumferential surface 204 along axis 252.Along the zero line of the axis 250, and along the 1.0 ratio line of theaxis 250, the lowest point of the valley 224 may be located atapproximately eighty-five degrees along the inner circumferentialsurface 204 at points 260 and 262, respectively. In this manner theheight (distance from the outer circumferential surface 202), of theinner circumferential surface 204 may vary in the circumferentialdirection along the axis 252 and along the axial direction along theaxis 250. As a result, directed convergence of the oil film in theinterface between the shaft 18 and the bearing 200 may be provided asshown by the arrows between valley 226 and peak 223. In a number ofvariations a similar profile with single or directed convergence may beprovided at the outer circumferential surface 202 or on the surface ofthe housing in the bore. The outer circumference of the shaft 18 may beformed substantially circular, or with a small eccentricity or a smalldeviation from circular, in each case in the range of a few microns.

With reference to FIG. 13, in a number of variations a method of makinga bearing such as the bearings 24, 26, 50, 70, 90, 130, 200, may involvea machine 300 that may be a high-speed magnetically levitated machinetool and spindle assembly. The machine 300 may include a rotor 302 whichmay include a boring bar 304 for interacting with a workpiece 306, whichmay be a bearing. The rotor 302 may include a section 308 with motorlaminations and rotor bars. The rotor 302 may include sections 309 withmagnetic bearing laminations. The rotor 302 may be surrounded by motorwindings 310 that may interact with the section 308 to effect rotationof the rotor 302. The rotor 302 may be surrounded by axial bearingwindings 317 that may interact with the rotor thrust disc 319 to supportthe rotor 302 along the axial direction 314 and also may direct theaxial trajectory 314 of the boring bar 304. The rotor 302 may besurrounded by radial bearing windings 316 that may interact with thesections 309 to support the rotor 302 and to direct the radialtrajectory 318 of the spindle 304. A sensor 320, which may be multiplesensors, may monitor and report the radial position of the rotor 302 andsensor 321, which may be multiple sensors, may monitor and report theaxial position of the rotor 302 in the axial direction. A sensor 323 maymonitor angular position of the rotor 302. An electronic controllersystem 322, for example may include components like a motor drive,magnetic bearing amplifiers and control components may control power toeach of the motor windings 310, the axial bearing windings 317, theradial bearing windings 316 and the linear slide 325. Tracking of therotor 302 may be controlled by monitoring and recording data fromsensors 320, 321 and 323, and controlling the operation of the axialbearing windings 312, the radial bearing windings 316 and the linearslide 325, to direct the axial and radial trajectories 314, 318 relativeto the bearing 306. In other variations some or all of the functions ofthe motor windings 310, the axial bearing windings 317 and the radialbearing windings 316 may be combined into a fewer number of windings ormay be provided in coordination with a greater number of windings. Alinear slide 325 may be controlled by the controller components 322 tocoordinate motion 315 of the workpiece 306 with the radial 318 and axial314 trajectory of the rotor 302.

In operation of the electronic controller components 322, methods,algorithms, or parts thereof may be implemented in a computer program(s)product including instructions or calculations carried on a computerreadable medium for use by one or more processors to implement one ormore of the method steps or instructions. The computer program productmay include one or more software programs comprised of programinstructions in source code, object code, executable code or otherformats; one or more firmware programs; or hardware description language(HDL) files; and any program related data. The data may include datastructures, look-up tables, or data in any other suitable format. Theprogram instructions may include program modules, routines, programs,objects, components, and/or the like. The computer program may beexecuted on one processor or on multiple processors in communicationwith one another.

In a number of variations, the program(s) may be embodied on computerreadable media, which can include one or more storage devices, articlesof manufacture, or the like. Illustrative computer readable media mayinclude computer system memory, e.g. RAM (random access memory), ROM(read only memory); semiconductor memory, e.g. EPROM (erasable,programmable ROM), EEPROM (electrically erasable, programmable ROM),flash memory; magnetic or optical disks or tapes; and/or the like. Thecomputer readable medium also may include computer to computerconnections, for example, when data may be transferred or provided overa network or another communications connection (either wired, wireless,or a combination thereof). Any combination(s) of the above examples isalso included within the scope of the computer-readable media. It istherefore to be understood that methods may be at least partiallyperformed by any electronic articles and/or devices capable of executinginstructions corresponding to one or more steps of the disclosedmethods. The electronic controller 322 may implement programs to movethe spindle 302, boring bar 304 and axial slide 325, through a range ofradial, and may be combined with axial, trajectories combined to cut adesired surface on the inner circumferential surface 324 of theworkpiece 306. The electronic controller 322 may be programmed with thedata to control cutting such as to effect the profile charted in FIG. 12by dimensionally varying the radial and axial trajectories 318, 314 ofthe spindle 304.

In a number of variations the boring bar 304 may include a cutting tool330. With reference to FIG. 14, the cutting tool 330 may include a tip332. The tip 332 may include a radius 334 which may be in the range of0.1-1.0 millimeters. The tip 332 may include a radius 336 that may be inthe range of 0.1-3.0 millimeters. The radius 334 may join with theradius 336 at the terminal point 340 of the tip 332. In other variationsa flat or angled surface may be interposed between the radius 334 andthe radius 336 at the terminal point 340. With reference to FIG. 15, thecutting tool 330 may be illustrated contacting the workpiece 306 in acutting operation with the tip 332 rotating around an axis 342 so thatthe tip 332 may be described as travelling into the view of FIG. 15. Thetip 332 may make a cutting pass around the axis 342 at a location 342with the terminal end 340 contacting the workpiece 306 at a cutting area344, which cuts along a circumferential and axial length of theworkpiece 306. With reference to FIG. 16, the tip 332 may make asubsequent cutting pass at location 346 with the terminal end 340contacting the workpiece 306 at an area 350. The area 350 may overlap348 with the area 342 to provide the desired profile as the cutting tool330 advances along the workpiece 306. With reference to FIG. 17, as thetip 332 is making a cutting pass such as at position 342 or 346, theterminal end 340 may be separated from the workpiece 306 in anintermittent fashion so as to provide a milling type cut. A milling typecut may be advantageous for heat management and chip formation, and toadd scallop features after profiles 212 are formed. In a number of othervariations the terminal end 340 may remain in contact with the workpiece306 during cutting, which may provide a boring type cutting action. In anumber of other variations the cutting tool 330 may be guided to providea combination of milling-type and boring-type cutting actions at variouspositions on the workpiece 306 through control of the axial and radialtrajectories 314, 318. In a number of other variations as illustrated inFIG. 18, the cutting tool 330 is illustrated from an end of theworkpiece 306 with cutting action being directed in a clockwisedirection 352. The tip 332 may be directed through the axial and radialtrajectories 314, 318 to contact the workpiece 306 at a leading angle at354 or at a trailing angle at 356. The angle 354 or 356 may be selectedrather than a perpendicular orientation relative to the workpiece 306 tooptimize cutting performance. The angle 354 or 356 may allow the cuttingtool 330 and rotor 302 to follow its preferred orientation based on itsresponse motion due to dynamic and static forces on the rotor 302. In anumber of variations the desired profile may be achieved with transitiondiscontinuity, such as from a peak to a valley, controlled bycoordinating the radial and axial trajectories 318, 314. Control of thecutting tip 332 through tracking control of the windings 316 and 317during their operation as actuators to manipulate the rotor 302. In anumber of variations the workpiece 306 may be fed by linear slide 325toward the rotor 302 in combination with radial and axial control of therotor 302.

Through the foregoing variations a bearing, and a method of making abearing with directed convergence is provided. The description ofvariants is only illustrative of components, elements, acts, product andmethods considered to be within the scope of the invention and are notin any way intended to limit such scope by what is specificallydisclosed or not expressly set forth. The components, elements, acts,product and methods as described herein may be combined and rearrangedother than as expressly described herein and still are considered to bewithin the scope of the invention.

Variation 1 may involve a bearing system that may include a bearingelement that may have a first surface. A mating element may have asecond surface that may face the first surface. A fluid film interfacemay be defined between the first and the second surfaces. The matingelement may rotate about an axis and relative to the bearing element. Anaxial direction may be defined parallel to the axis. A circumferentialdirection may be defined encircling around to the axis. The firstsurface may have a profile that may vary in the axial direction and thatmay varies in the radial direction. The profile may direct a fluidpresent in the fluid film interface in both the axial andcircumferential directions.

Variation 2 may include the bearing system according to variation 1wherein the profile may have a shape that is smooth without edged steps,not including any other feature that may intersect the profile forexample, but not limited to, features such as oil inlet holes and/or oilfeed grooves.

Variation 3 may include the bearing system according to variation 1 or 2wherein the first surface may be an inner circumferential surface of thebearing. The profile may include a number of valleys that may definetroughs along the first surface, and may include a number of peaks thatmay define ridges along the first surface. The troughs and ridges mayalternate around the inner circumferential surface.

Variation 4 may include the bearing system according to variation 3wherein the bearing element may include a first end and may include anopposite second end spaced from the first end in the axial direction.Each of the troughs and valleys may extend from the first end to thesecond end.

Variation 5 may include the bearing system according to variation 3wherein the bearing element may include a first end and may include anopposite second end spaced from the first end in the axial direction. Afirst dam may be defined at the first end and a second dam may bedefined at the second end. Each of the first and second dams may extendinward in the radial direction further than the inner circumferentialsurface. Each of the troughs and valleys may extend from the first damto the second dam.

Variation 6 may include the bearing system according to variation 3wherein each of the troughs and valleys may extend from a first end to asecond end. The bearing may be shaped as a hollow cylinder and maydefine an open area inside the hollow cylinder. The innercircumferential surface may face into the open area. The innercircumferential surface may extend three hundred and sixty degreesaround the open area. Each of the ridges at a defined axial locationsuch as the midpoint of the bearing along the axis may be offset aroundthe inner circumferential surface from all points on the respectiveridge that may be located outward toward the first or second end fromthe midpoint.

Variation 7 may include the bearing system according to variation 3wherein each of the troughs and valleys may extend from a first end to asecond end. The bearing may be shaped as a hollow cylinder and maydefine an open area inside the hollow cylinder. The innercircumferential surface may face into the open area. The innercircumferential surface may extend three hundred and sixty degreesaround the open area. Each of the ridges at its first end may be offsetaround the inner circumferential surface from all points on therespective ridge that may be located toward the second end from thefirst end.

Variation 8 may involve a method of making the bearing system accordingto variation 3 and may include providing a machine with a rotor.Magnetic levitation of the rotor may be provided. The rotor may beprovided with a cutting tip. The rotor may be directed through at leastone of a radial, or an axial trajectory using the magnetic levitation.The profile of the bearing element on the inner circumferential surfacemay be cut with the cutting tip.

Variation 9 may include the method according to variation 8 and mayinclude providing the cutting tip with a radius so that the cutting tipincludes a terminal end that may contact the bearing at a cutting area.

Variation 10 may include the method according to variation 8 and mayinclude orienting the cutting tip at an angle that is perpendicular to,or other than perpendicular to, the inner circumferential surface.

Variation 11 may include the method according to variation 8 and mayinclude contacting the inner circumferential surface intermittently withthe cutting tip while cutting the profile.

Variation 12 may involve a bearing system that may include a bearingelement in the shape of a hollow cylinder with an open center. Acylindrical wall of the bearing element may define an innercircumferential surface facing the open center. A shaft may extendthrough the open center and may rotate about an axis and relative to thebearing element. A radial direction may be defined perpendicular to theaxis. A fluid film interface may be defined between the innercircumferential surface and the shaft. A fluid may be present in thefluid film interface. The inner circumferential surface may have aprofile that may be shaped with a first variation in the radialdirection and with a second variation in the axial direction. A directedconvergence of the fluid may be provided with one or more components inat least one of the axial direction, or the radial direction, as theshaft rotates relative to the bearing element.

Variation 13 may include the bearing system according to variation 12wherein the inner circumferential surface may have a circumferenceextending completely around the axis. The profile may include a numberof valleys that may define troughs along the inner circumferentialsurface and may define a number of peaks defining ridges along the innercircumferential surface. The troughs and ridges may alternate around thecircumference of the inner circumferential surface.

Variation 14 may include the bearing system according to variation 13wherein each of the ridges may extend in the axial direction in acurve-shaped arc, or in a linear orientation.

Variation 15 may include the bearing system according to variation 12wherein the inner circumferential surface may vary in the axial andradial directions. Smooth ramp like structures may be formed from eachvalley to an adjacent peak. The circumferential and axial components ofconvergence may be in an uphill direction from the valley to the peak.

The above description of select variations within the scope of theinvention is merely illustrative in nature and, thus, variations orvariants thereof are not to be regarded as a departure from the spiritand scope of the invention.

What is claimed is:
 1. A turbocharger hydrodynamic journal bearingsystem comprising a bearing element comprising a first surface definedby an inner diameter of the bearing element and a second surface definedby an outer diameter of the bearing element, a shaft comprising a thirdsurface facing the first surface with a fluid film interface definedbetween the first and the third surfaces, wherein the shaft rotatesabout an axis and relative to the bearing element, wherein an axialdirection is defined parallel to the axis, wherein a circumferentialdirection is defined around the axis, wherein the bearing element isconstructed and arranged to at least one of rotate at a speedsubstantially less than the shaft and about the same axis as therotating shaft or precess and not rotate about the rotating shaft, abearing housing comprising a fourth surface defined by an inner diameterof the bearing housing, wherein the fourth surface surrounds the secondsurface of the bearing element, and wherein one of a hydrodynamic or asqueeze-film damper fluid film interface is defined between the secondand the fourth surfaces, wherein the second surface has a continuousrigid circumferential surface, wherein the first surface has anon-circular circumferential profile extending 360 degrees around thethird surface, wherein largest radial points of the non-circularcircumferential profile of each axial perpendicular cross-section of thefirst surface comprise an axial curved shape that narrows at each end ofthe bearing element and bulges near a middle portion of the bearingelement, and wherein smallest radial points of the non-circularcircumferential profile of each of the axial perpendicular cross-sectionof the first surface comprise an axial cylindrical shape over an axiallength of the bearing element.
 2. A turbocharger hydrodynamic journalbearing as set forth in claim 1, wherein the first surface comprises atleast one first oil feed hole, and wherein the third surface comprisesat least one second oil feed hole or a circumferential oil groove.
 3. Aturbocharger hydrodynamic journal bearing system comprising a bearingelement that has a first surface, a mating surface element that has asecond surface facing the first surface with a fluid film interfacedefined between the first and the second surfaces, the mating surfaceelement is constructed and arranged to rotate about an axis and relativeto the bearing element, wherein an axial direction is defined parallelto the axis, wherein a circumferential direction is defined around theaxis, wherein the bearing element is constructed and arranged to atleast one of rotate at a speed substantially less than the matingsurface element and about the same axis as the rotating mating surfaceelement or precess and not rotate about the rotating mating surfaceelement, wherein the first surface has a non-circular circumferentialprofile extending 360 degrees around the mating surface element, whereinthe first surface has a non-cylindrical non-constant axial profile, andwherein the non-circular circumferential profile located at the firstend has a continuous offsetting circumferential phase shift as locatedtoward the second end from the first end.
 4. A turbocharger hydrodynamicjournal bearing system comprising a bearing element that has a firstsurface, a mating surface element that has a second surface facing thefirst surface with a fluid film interface defined between the first andthe second surfaces, wherein the mating surface element is constructedand arranged to rotate about an axis and relative to the bearingelement, wherein an axial direction is defined parallel to the axis,wherein a circumferential direction is defined around the axis, whereinthe bearing element is constructed and arranged to at least one ofrotate at a speed substantially less than the mating surface element andabout the same axis as the rotating mating surface element or precessand not rotate about the mating rotating surface element, wherein thefirst surface has a non-circular circumferential profile extending 360degrees around the mating surface element, wherein the first surface hasa non-cylindrical non-constant axial profile, wherein the non-circularcircumferential profile located at the first end has a continuousoffsetting circumferential phase shift as located increasingly towardthe second end from the first end, whereas at a predetermined axiallocation between the first end and the second end, the continuing offsetcircumferential phase shift ceases and reverses until the second axialend is back to being equal to the first axial end.